I actually "stole" the pic from the Mercedesshop.com's feature on the 300E cars :-)

Peter,

My temp comes on pretty quick depending the temp I set and in the auto mode. In about 5mins it gets pretty warm but most of the time what I do is select the defroster for the front and rear and once the main windows are clear just switch it on either Economy setting or heat from the botton vents only since I always have a jacket on.